Spatial frequency rows in the straite visual cortex

We have recorded the unitary activity of the neurons of area 17 of the cat either in penetrations perpendicular to the surface of the cortex or parallel to it. We have examined the functional architecture of this cortical area with respect to the spatial frequency of the visual stimulus (sinusoidal gratings) at which each neuron is most sensitive. In penetrations perpendicular to the surface of the cortex (columns) the cells of the various layers or even of the same layer have the same preferred orientation but different preferred spatial frequencies. In penetrations parallel to the surface of the cortex the cells of the same layer or sublayer present a variety of preferred orientations, but maintain the same preferred spatial frequency and visual acuity over long microelectrode track distances.